1. Field of the Invention
This invention relates to sleep prevention devices, especially relates to multi function optic sleep prevention devices for vehicle drivers on wheel.
2. Description of Prior Art
The traffic records have shown that driver's falling asleep on wheel is a most dangerous accidence maker. A few seconds of sleep may cause deadly disaster to a high way driver while driving. Only in 1999, there were over 100,000 traffic accidents caused by sleepy drivers. In the past a few decades, especially in the past twenty years, a lot of efforts have been towards this problem. There have been many patents related to this subject published by now. Most concentrate on the following approaches: (1) Monitoring drivers' eyelid movement, such as U.S. Pat. Nos. 5,786,765, 5,745,038, 4,875,030, 1,863,243, etc.; (2) Detecting head's tilting, such as U.S. Pat. Nos. 5,684,461, 3,906,478, etc; (3) Sensing other body's symptoms, U.S. Pat. No. 5,585,785, etc. None of them has, however, become a commercial size of industry. There are some common difficulties for them. Firstly, a human body's performance is complicated, sometimes like a puzzle or a paradox. For example, closing eye for about 2-3 seconds during driving may be a dangerous sleeping symptom, or it may not be a symptom if the driver only nearly closes eyes for having a short relax or avoiding seeing too bright environment. And about 2-3 seconds' head's tilting may be very important, or may have no relation to sleepiness. Secondly, the detecting resolution of the monitors themselves may not meet the needs in some situations. For example, an eye-monitor is generally supposed to be carried by an eyeglass or a like, or installed in somewhere inside the driver chamber. It is hardly to accurately target the same position of an eye when in use. Also, the eye brow may influence the light signals when an eye is very nearly closed, so it is difficult for a monitor to verify the real fact. The detected results, however, are crucially important for an alarming system, and must be precisely made within a few seconds before too late, and only correct alarming is welcome by users.
In this paper patent application, the authors put forward a dual function optic sleep preventing device for drivers, based on monitoring both eyelid's movement and the head's tilting at the same time. The new system combines an optic eye-monitor with a micro optic tilt switch together to make a double check on a driver's sleeping symptom. The eye-monitor comprises an infra signal emitter and a sensing device. The tilt switch uses a micro optic monitor to detect the position of a small ball rolling in a small close tube inside the switch while tilting. Both the devices may be carried by an eyeglass or a like, or a head mounting device to set on a user's head when in use. When one monitor finds out a possible sleep symptom, the other will check the case independently at the same time. When the case is ascertained to be a dangerous one, a corresponding signal is created by a related circuits to stimulate an alarming unit. The alarming is principally divided into two levels: A pre-alarming and a fully alarming. The former is to test the state of a driver and further check if the driver needs a stronger warning. In the mean time, the number of the events is recorded by a counter. If the driver does response a pre-alarming, but repeats similar symptoms again and again and even more often afterwards, eventually reaching a predetermined number of times, or the driver does not response to a pre alarming for a certain limited waiting period of time, a fill alarming is immediately followed.
This present system has greatly improved the existing systems. An approximate estimation on the reliability of a dual system at early sleepy stage is as follows: if let u be the ratio of failure of a single eye-monitor, and v that of a tilt switch, the ratio by a dual monitoring system would be f=uxv. The corresponding reliability is then r=1-f. For example, if u=20% and v=20%, then f=4% and r=96%. In other words, the corresponding reliability of the present system would be greater than 95%. Even each single one is so bad with a failure ratio of 30%, we still may obtain a successful ratio of 91%.